Generator control



April b1935- J. J. DRABIN 1,999,871

GENERATOR CONTROL Filed May 28, 1934 JOHN J DIM BIN INVENTOR QA P. Mm

ATTORNEY Patented Apr. 30, 1935 UNITED STATES PATENT OFFICE Claims.

My invention relates to generator control and has particular reference to devices and arrangements ior controlling the voltage oi! a battery,

chargin generator.

My invention has for its object to provide a voltage control system for generators connected with automobile engines or other similar prime movers of variable speed, preferably when such generators float on the batteries.

Another object of my invention is to provide voltage as caused by the diilerent degree of charge of the battery. For this purpose I use a rotary member operatively connected with the electromagnetic device, such as a solenoid or electric motor, this rotary member having curved contact surfaces bearing against the resistor and progressively short circuiting the same. With my device it is possible to judge of the degree of chargeot the battery by the angular position of the short circuiting rotary member, and in order to iacilitate the observation of its position, I provide an extension on its shaft with an indicating hand moving around a calibrated dial. The latter may be conveniently placed on the dash board of an automobile. I also use the rotary member to operate the battery cut-out switch, thereby combining the voltage regulator and the cut-out switch in one apparatus.

While the electromagnetic device exerts a positive pull on the rotary member when the generator voltage rises, the return movement is controlled by a spring. In order to use this spring as a temperature compensating device, I make it of two metals having different temperature coeillcients so adjusted, that the resiliency of the com-' posite bimetallic spring varies in accordance with the variations in the resistance of the field rheostat and windings caused by the temperature variations. I

I also provide a supplementary resistor connected with the voltage regulating rheostat with a switch for short circuiting this resistor. I mechanically connect this switch with a switch controlling the automobile lamps or similar load so that the supplementary resistor becomes short circuited when the lamps are switched in, thereby providing a higher charging voltage and preventing the excessive discharge of the battery. With thelamps switched oil, the supplementary resistor is connected in, reducing the generator voltage.

In order to indicate when the generator ceases 5 to charge the battery and is disconnected by the cut-out switch, I provide a visual signal, such as a lamp, operated when the cut-out switch is -My invention is more fully described in the i accompanying specification and drawing in which- Fig. l is a diagrammatic .view of my mechanism and electrical connections, Fig. 2 is a similar view of a modified device, Figs. 3 and 4 are two views of another modification, Fig. 5 is'a partial view of another modification, and Fig. 6 is a partial view 01' still another modification.

My voltage regulating deviceconsists 01' two flexible wires or cables I made of a suitable resistance alloy, such as nichrome. These cables are attached at one end to curved metal plates 2 mounted on a block 3 made of an insulating ma-. terial. The plates are made of some metal havinghigh electrical conductivity, for instance copper, so that portions of cables lying on the plates become short circuited, the total resistance of the cables being correspondingly reduced. The other ends of the cables are attached to an insulation block 4 and are connected together by a metal bar 5. The plates 2 are insulated from each other and connected by metal strips with screws 6 to which flexible insulated leads 'I are attached. The other ends of these'leads are connected with leads I and 9. The block 3 is rotatively mounted on a stationaryshaft I 0 held in brackets 14. A spiral spring H is attached with one end to the shaft III, the other end being attached to the block 3 by a screw II. The end of the spring has an elongated slot ii for the screw I! in order to provide for the adjustment of the tension of the spring. The spring itseli consists of two'layers, II and II, made of two metals having different temperature coefllcients, so that the spring changes its resiliency for different temperatures, thereby compensating for the change or resistance of the wires I and other parts of the electrical system with the variations in temperature. An iron plunger II is suspended from the block 4 and slides in coils II and it. A helical spring I1 is attached to the end of the plunger l4 and is hooked to a tension adjusting screw l8 mounted in a stationary bracket J9.

The lead 9 is connected with a generator 2| through a lead 22. The other generator terminal "turning the block 3.

is connected with the ground at 23 and with one end of a field winding 24. The other end of the winding is connected by a lead 25 with the lead 8 through a supplementary resistor 26. The latter may be short circuited by a switch 21 me chanically connected with a switch controlling the lamps of an automobile (not shown) or other load, such as radio etc. The generator lead 22 is connected with a shunt winding I6 of a magnet operating the plunger I4. The other end of the coil I6 is grounded at 29. A lead 30 extends from the lead 9 to a contact spring 3I mounted above a contact block 32, the members 3| and 32 forming a cut-out switch for a battery 33. The latter is connected by a lead 34 with the series coil I5 of the magnet, the other battery terminal being grounded at 35. A rod 28 engages the bar 3I and is slidably mounted in a lug 36 at the end of the block 4. A spring 31 presses the rod 28 against the bar 3!. A stationary dial 38 is supported on the end of the shaft I and is calibrated in convenient units indicating the degree of charge of the battery. A hand or pointer 38 is attached to the block 3 and extends to the front of the dial. The operation of my device is as follows.

With the engine standing still, the generator 2| is disconnected from the battery by the cut-out switch, the plunger I4 being raised to its highest position by the cables I pulled up by the block 3 under action of the retrieving spring I I. After the engine is started and the generator begins to build up its voltage, the coil I6 will begin to pull the plunger I4 down. As soon as the generator voltage reaches the charging value, i. e. somewhat higher than the battery voltage, the contact points 3I and 32 will be closed by the pressure from the rod 28, thereby connecting the series coil I in the circuit between the generator and the battery and permitting the current from the generator to fiow into the battery. The circuit closing point is determined by the combined resistance of the springs I I, I1 and 31, the spring I1 working in opposition to the other two. The closing point can be adjusted by turning the screw I8, and some adjustment can be also made by shifting the end of the spring II under the screw I2. The latter adjustment, however, is used principally for regulating the temperature compensation feature of the bi-metallic spring I I. With the further increase in the engine speed the generator voltage will be also increased with a result that the magnet will pull stronger on the plunger I4 thereby pulling down the cables I and The longer free portions of the cables will have greater resistance thereby reducing the current in the generator field winding and, as a result, bringing down its voltage. The indicating pointer 39 will show the position of the block 3 thereby indicating also the condition of the battery charge, taking into consideration the known engine speed. Additional regulation is provided by the resistance 26 which is switched oiI or short circuited when there is a heavy lamp load. The flexible cables 1 attached to the block 3 at the ends of connectors 26 permit the limited rotational movement of the blockl. The other ends of these cables are attached to stationary iansulated supports and connected with'the leads The series coil I5 increases the strength of the magnet pull by compounding its action, so that it responds to the rise of the current as well as of the voltage. With this arrangement -no other voltage regulation is necessary, and the generator may be of an ordinary shunt wound type without the regulating third brush.

The supplementary resistance 26 may be connected in any convenient place in the generator field circuit.

A modified arrangement is shown in Fig. 2. Here the resistor cables I are wound on a cylinder 4| covered on the periphery with a single metal plate 42 which establishes metallic connection between the cables I. The free ends of thecables are connected to the upper end of an insulation block 43. Metal strips 44 extend from the ends of the cables along the sides of the block and are engaged by contact springs or brushes 45 connected as shown with the field winding 24 of the generator 45. A plunger I4 is operated by a single solenoid 41 connected with the generator through the ground 29. Springs II and I1 control the tension of the cables. A third strip 48 is connected by a flexible cable 49 with the battery 33 through a cut-out switch 48 of an ordinary construction. This cut-out switch has two windings, one connected in shunt with the generator, the other in series, the construction and connections being similar to the windings shown in Fig..l. The connections of the cut-out switch are not shown, being of an ordinary and well known type.

In case the auxiliary series coil [5 is omitted, the generator 46 may be of a voltage regulating type with a third brush 50.

Another modification is shown in Figs. 3 and 4. Here the resistor cables I are stretched between stationary terminals 5I and 52 connected with leads 25 and 9 respectively, and an insulation block 53. The upper ends of the cables are connected together on the block by a con- 'nector 54. The block 53 is supported on the lower end of a fiat spring 55 the upper end of which is mounted on a shaft 56. A rotary member 51 is in the shape of a curved bar pivotally mounted on a shaft 58 and is provided with an arcuate iron armature or plimger 59. The curved bar 51 is made of metal and is adapted to short circuit the portion of cables I against which this bar is pressed. The tension of the spring 55 is regulated by a screw 60 supported in a bracket 6I. The magnet coils I5 and I6 are connected as in Fig. 1. The battery cut-out switch is formed of two spring contact members 62 and 63 which are connected together when the bar 51 begins to recede from the cables I. The contact spring 62 also closes a contact with a bar 64 connected with an electric lamp 65 or similar signalling device. The lamp is burning when the battery is disconnected from the generator thereby indicating that the battery is being discharged. With this arrangement it is not necessary to have an ammeter on the dash board.

Another modification is shown in Fig. 5. The cylinder 4| is mounted on a shaft 66 on which a rotary armature 61 is mounted. The armature rotates between the poles of a magnet 63. Otherwise the device is similar'to the devices shown in Figs. 1 and 2.

Another modification is shown in Fig. 6. Here the resistor is formed in the shape of two fiat springs 69 and joined together at one end and attached to a shaft 1 I. The latter carries a motor armature 61. The springs are bent in the shape of spirals with progressively increasing clearance between them. The ends of the spirals are mounted on an insulation block 12 and connected with leads 9 and 25. With this arrangement the greater angle of rotation causes a larger portion of the spirals to come in contact with each other. The armature 81 is therefore placed so in the field met that the spirals become unwound with the increased voltage of the generator. The resistor, however, may be connected in parallel with the field winding, in which case the spirals must be wound closer with the increased voltage.

Such alternativearrangement of the resistor can be made, of course, also with the modiilcations shown in the other figures.

Important advantages of my generator control are that it provides an automatic voltage regulation, taking care of the variations of the engine speed, as well as of the variations of the battery voltage during its charge. My control has no vibrating or sparking contacts, the resistance being varied gradually and automatically. and no other voltage regulating devices are necessary with my system. I also combine in a single apparatus the voltage regulator and the battery cut-out switch. I also provide temperature compensating device, and an indicator showing the condition of the battery.

My voltage regulator tends to maintain the battery fully charged. At the same time it eliminates the undesirable possibility of overcharging the battery. This is accomplished by the setting of the regulator to a certain safe voltage which it will not exceed. t Then whenever the battery reaches its highest charge, the greatest resistance is introduced into the generator field, thereby equalizing the difierence between the battery and generator voltages.

I claim:---

. 1. In a generator control, the combination with a resistor consisting of two flexible cables in parallel alignment, of a rotary member, the outer surface of said member being made of an electricity conducting material, means to stretch said cables, said rotary member being adapted to engage said cables with its outer surface thereby short circuiting a variable portion of their length, an electric generator for charging a storage battery, said resistor being connected with the field winding of said generator, an electromagnetic means-for rotating said rotary member, said electromagnetic means being energized by said generator, and means for connecting said generator with said battery when the generator voltage reaches a predetermined charging value.

said connecting means being adapted to be operated by said electromagnetic means.

2. In a generator control, the combination with a resistor consisting of two parallel flexible cables, of a rotary member adapted to engage said cables with its curved outer surface, said surface being of a' conducting material and adapted to short circuit the portion of said resistor in contact with said surface, a battery charging generator, said resistor being connected with the shunt fleld winding of said generator, an electromagnetic device for rotating said member, said device being adapted to be energized by the current from said generatonand means to connect said generator with said battery when the voltage of said generator reaches a predetermined charging value, said connecting means being adapted to be operated by said electromagnetic means.

'3. In a generator control, the combination with a resistor consisting of two parallel flexible cables, of a rotary member adapted to engage said cables with.its outer curved surface, said surface being of a conducting material and adapted to short circuit the variable portion of length of said cables, a resilient means for keeping said cables under tension, a battery charging generator, an electromagnetic means for rotating said member, said electromagnetic means being adapted to be energized by the current from said generator, a retrieving means for said rotary member, said resistor being connected with the field winding of said generator, and means for connecting said generator with said battery when the generator voltage reaches a predetermined char in value, said means beingadapted to be operated by said electromagnetic means.

4. In a generator control, the combination with a resistor of a rotary member in a cooperative relation with said resistor, said resistor being connected with the field winding of a battery charging generator, said rotary member being adapted to short circuit a variable portion of said resistor, a magnet adapted to be energized by said generator and further adapted to turn said rotary member, and a retrieving spring on said rotary member, said spring being made of two metals having different temperature coeflicients for varying the resistance to rotation of said member in accordance with variations in the temperature.

JOHN J. DRABIN. 

